What is the genotype of a red cat? - briefly
The genotype of a red cat is primarily determined by the presence of the orange (O) allele on the X chromosome. This allele is responsible for the production of pheomelanin, which results in the red or orange fur color typically seen in cats.
What is the genotype of a red cat? - in detail
Understanding the genotype of a red cat involves delving into the complex world of feline genetics, particularly focusing on the genes responsible for coat color. Red fur in cats is a result of specific genetic interactions that determine the production of pheomelanin, a type of melanin that gives rise to red and yellow pigments.
The primary gene responsible for red coloration in cats is the O locus, also known as the Orange locus. This locus has two alleles: the dominant allele (O) and the recessive allele (o). The presence of at least one dominant O allele results in the production of pheomelanin, leading to red or orange fur. Cats with two recessive o alleles will not produce pheomelanin and thus will not exhibit red fur.
It is crucial to note that the O locus is located on the X chromosome, making it a sex-linked trait. Females, having two X chromosomes (XX), can be homozygous (OO or oo) or heterozygous (Oo) for the orange allele. Male cats, with one X and one Y chromosome (XY), can only be hemizygous, meaning they will express the phenotype of the single allele present on their X chromosome. This genetic configuration explains why red males are relatively common, while red females are rarer and often exhibit tortoiseshell or calico patterns due to X-inactivation, a process where one of the X chromosomes in each cell is randomly inactivated.
Additionally, modifier genes can influence the exact shade of red, ranging from deep red to light orange. These modifiers can affect the intensity and distribution of pheomelanin in the fur, contributing to the diverse range of red hues observed in cats.
In summary, the genotype of a red cat is primarily determined by the presence of the dominant O allele at the Orange locus on the X chromosome. The interaction of this allele with other genetic factors and modifier genes results in the varied expressions of red fur seen in feline populations.